Things to consider.
Before you start calculating, there is a choice to make. Using different liquids can result in the final dough having a different acidity/alkalinity. Up to a certain point (around 3.0pH) more acidity can greatly influence the hydration capacity of gluten. The more acidic the dough the more water you can add to it.
On the other hand, the more neutral/alkaline the looser and softer the dough will be and the less water it will be able to handle. Milk has a pH of around 7. The other milk products are more acidic at around pH 4.5.
So, you can either increase the hydration of the dough to compensate or stick with the same hydration and have a stiffer dough. The advantage of having a stiffer and stronger dough is that it can take more fermentation. It can produce a taller loaf and it can be fermented for longer. The advantage of a higher hydration is that it will result in a more open crumb and better keeping quality.
I chose to aim for the same hydration in all breads to really see the difference.
How to substitute water for any particular milk product.
We know that milk & buttermilk are both 90% water. Yogurt is 88% and sour cream is 74%.
The base recipe contained 140g flour, 95g water, 1.5g yeast, 2.5g salt.
The hydration of that recipe was 68%. 140 x 0.68 = 95g water.
To calculate the amount of milk or milk product needed, we must divide the water content in the base recipe by the water content percentage of each ingredient.
Milk (95g : 90% = 105g)
Buttermilk (95g : 90% = 105g)
Yogurt (95g : 88% = 108g)
Sour cream (95g : 74% = 128g)
If you were to make a recipe using fat and sugar, then consider the amount of fat and sugar in each ingredient and adjust the rest of the recipe accordingly.
